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Biomechanical response of selected structures of the knee joint to mechanical loads
Horňáková, Lenka ; Jelen, Karel (advisor) ; Navrátil, Leoš (referee) ; Mlynárik, Vladimír (referee)
Title: Biomechanical response of the knee meniscus to the axial loads Work Title: The quantification of the structural changes in deep layer of the knee meniscus using the standardized axial loading Purpose: Due to the internal structure of the knee joint, the ability to characterize and quantify the dynamic response of the meniscal tissue directly in vivo is highly problematic. The main purpose of this study was to investigate the behavior of the meniscus under loading conditions, using parametric MR imaging. Methods: Subjects with no history of knee pain or meniscal problems were included in the study (mean age 27.8 ± 1.3 years). To obtain values of relaxation times T2* in the meniscus, the vTE sequence was used with 10 echoes ranging from 0.8 to 10.1 ms. This has resulted in minimizing the echo time, which is an advantage when differentiating meniscal tissue from surrounding components. First of all, an unloaded limb was scanned and immediately after, the limb loaded half of the person's weight was measured repeatedly in 4 consecutive scans. A custom - made diamagnetic apparatus was developed to simulate stress conditions on the lower limb in a conventional MR scanner. At each 6:10 min measurement, the knee joint was scanned in 64 sections, each image displaying a 1.3 mm section.The two -...
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Biomechanical response of selected structures of the knee joint to mechanical loads
Horňáková, Lenka ; Jelen, Karel (advisor) ; Navrátil, Leoš (referee) ; Mlynárik, Vladimír (referee)
Title: Biomechanical response of the knee meniscus to the axial loads Work Title: The quantification of the structural changes in deep layer of the knee meniscus using the standardized axial loading Purpose: Due to the internal structure of the knee joint, the ability to characterize and quantify the dynamic response of the meniscal tissue directly in vivo is highly problematic. The main purpose of this study was to investigate the behavior of the meniscus under loading conditions, using parametric MR imaging. Methods: Subjects with no history of knee pain or meniscal problems were included in the study (mean age 27.8 ± 1.3 years). To obtain values of relaxation times T2* in the meniscus, the vTE sequence was used with 10 echoes ranging from 0.8 to 10.1 ms. This has resulted in minimizing the echo time, which is an advantage when differentiating meniscal tissue from surrounding components. First of all, an unloaded limb was scanned and immediately after, the limb loaded half of the person's weight was measured repeatedly in 4 consecutive scans. A custom - made diamagnetic apparatus was developed to simulate stress conditions on the lower limb in a conventional MR scanner. At each 6:10 min measurement, the knee joint was scanned in 64 sections, each image displaying a 1.3 mm section.The two -...
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An empirical analysis of legal reasoning in the decisions of the Supreme Administrative Court of the Czech Republic 2004 - 2011
Mlynařík, Václav ; Kühn, Zdeněk (advisor) ; Wintr, Jan (referee)
The main aim of this thesis is to provide follow up for primary research that was published in the article of Marcin Matczak, Matyas Bencze and Zdeněk Kühn "Constitutions, EU Law and Judicial Strategies in the Czech Republic, Hungary and Poland," and to find out, in what extend it is possible to consider decision-making process of Czech administrative courts to be formalistic, or whether there have been any significant changes in strategies of adjudication since the primary research took place. First part of this thesis introduces organisational structure of Czech administrative courts, elaborates on the position of Supreme Administrative Court within that structure and shortly sums up its history. Second part of this thesis deals with theoretical questions regarding legal reasoning, both in general and with emphasis on judicial application of law, taking into account diverse ideologies and strategies that were formed developed by the doctrine. Final part of this thesis introduces outcomes of the follow up research that provided for quantitative analyses of case law of administrative courts in the years of 2003 to 2011. Matczak, Bencze and Kühn reviewed case law published in the official journal of administrative courts' decisions between 1999 and 2004 by marking usage of interpretational standards divided...
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Some comments on frequency selective excitation in newly proposed MRSI sequences
Starčuk jr., Zenon ; Horký, Jaroslav ; Starčuk, Zenon ; Mlynárik, V. ; Gruber, S. ; Moser, E.
In many pathologies it is desirable to compare the metabolism inside a lesion, near the lesion, and in healthy tissue. The diagnostic value of MRS is enhanced by spectroscopic imaging (MRSI), permitting the simultaneous acquisition of spatially resolved spectra. In this way, assessing metabolic information about different brain regions within a single examination is possible. As with all in vivo spectroscopy, low signal-to-noise ratio (SNR) is the fundamental limiting factor in MRSI due to very low concentrations of metabolites of interest. Proton spectroscopic imaging, however, offers additional technical challenges as compared to single-voxel techniques, especially if acquisition of short echo time (TE<30 ms) is required. Critical to the success of proton MRSI studies of the human brain is the elimination of the very intense water and lipid signals arising from outside the volume of interest (VOI). Water suppression in MRSI can be very problematic in MRSI, in which the achievable degree of water suppression is limited by B.sub.0./sub. and B.sub.1./sub. inhomogeneities and water T.sub.1./sub. variations, invariably present throughout the larger VOIs. Suppression of liquid signals (from bone marrow and subcutaneous fat) is often severely complicated due to the fact that their relaxation behavior differs substantially from that of water. One of the basic approaches used to reduce the undesired contamination if the MRSI signals of interest consists in the use of the STEAM or PRESS selective excitation of the VOI. Both STEAM and PRESS techniques suffer from some drawbacks. STEAM reduces the sensitivity of measurement, PRESS has higher RF power requirements.
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High resolution multivoxel spectroscopy of human brain at 3 Tesla
Mlynárik, V. ; Gruber, S. ; Starčuk, Zenon ; Starčuk jr., Zenon ; Horký, Jaroslav ; Moser, E.
Localisation in in vivo NMR spectroscopy can be achieved using different concepts. Single voxel localized spectroscopy exploits three slice selective pulses defining a cube (or a parallelepiped) in their intersection. By proper combination of spoiling gradients the excited magnetization outside the cube is dephased and does not contribute to the NMR signal. Another way of localisation is combination of slice selection with phase encoding of the NMR signal in the other two dimensions by means of gradient magnetic fields. The latter method is referred to as spectroscopic imaging and provides an array of spectra corresponding to individual voxels defined by the phase encoding. Further subdivision of the voxels is possible by Hadamard encoding of the excitation pulses.
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